Gosforth Nature Reserve Nature Journal: Small Mammals

Meet some of the small mammals of Gosforth Nature Reserve in this latest blog by local naturalist and volunteer, Christopher Wren.

It is a paradox that the most widespread and numerous mammals are the ones you are least likely to see. The UK populations of mice, shrews and voles number in the tens of millions yet because they are on the menu for Foxes, Weasels, owls and Kestrels they understandably keep a low profile. The main small mammals in Gosforth Nature Reserve are Bank Voles, Field Voles, Common Shrews, Pygmy Shrews, Water Shrews and Wood Mice. You might get a glimpse of a Bank Vole near the Lawrence Hide but other sightings are rare.

Partly because they hide away, small mammals are very underreported compared with, say, birds, butterflies and dragonflies. In the past any survey required a catch-and-release programme using Longworth traps which are expensive and tedious to use.  As the image quality from trail cameras has improved in recent years, they are being used more and more to record small mammals as well as larger ones.

The first video is recorded in a trail camera box built mainly for Weasels (more on that another time) but it also attracts the Weasels’ potential prey. The animals are all at the same distance from the same camera position so it is easy to compare their size. The Bank Vole has reddish-brown fur, a longish tail and prominent ears. In comparison, the Field Vole is larger and greyer and has flatter ears and a shorter tail (it is also known as a Short-tailed Vole). The Wood Mouse is about the same size as the Bank Vole and is mainly nocturnal, so filmed by infrared in black and white. It has huge eyes and ears (adaptations to its nocturnal existence) and a very long tail. The Common Shrew is smaller and is tricoloured on its sides – brownish flanks with a darker back and pale belly. The Pygmy Shrew is tiny, is only two-coloured on its sides, and has a longer, furrier tail.

Trail camera surveys of small mammals often just use an open-ended wooden box with the camera at the other end. Small mammals are always hungry so it relatively easy to attract them with bait. The next video shows a Common Shrew collecting food. Although it is an insectivore it clearly prefers sunflower seeds to dried mealworms. The first part of the video is at normal speed (not speeded up!) and the second is slowed to 1/10th normal speed so we can see what it is doing.

You can also record small mammals just by putting out some food in front of the camera, without any box. The last video was recorded by a pile of stones in my garden. It looked a promising spot so I put down sunflower seeds and casters (blowfly larvae). The Common Shrew again preferred the seeds. The second animal was a huge surprise, a Water Shrew, probably a juvenile dispersing away from its home territory. Also in the same stone pile were Bank Voles and Wood Mice. The Wood Mouse here is recorded on a camera that uses white light at night, rather than infrared.

It is easy to set up a trail camera to record in this way. Try it and see what turns up. And be sure to report your findings to Gosforth’s Wild Web.

Christopher Wren
Local Naturalist and Volunteer

Christopher Wren is a volunteer in Gosforth Nature Reserve and a local naturalist, interested in most areas of natural history, especially mammals and using trail cameras to study their behaviour.

Visit Chris’ blog for more updates on North East’s wildlife – TrogTrogBlog